Device and method for mixing the contents of a tank

ABSTRACT

Device  1  for mixing the contents of a tank  10  comprising a first pipe connecting body  20  arranged on a connecting flange  14  of a tank  10 ; a riser pipe  40  extending through the first pipe connecting body  20  into the tank; a mixing pipe  50  extending through said first pipe connecting body  20  into said tank; and a pump  60  whose outlet  64  can be connected at least to the mixing pipe  50  and whose inlet  62  can be connected both to the first pipe connecting body  20  and to the riser pipe  40 . Further a method for mixing the contents of a tank is claimed.

1. TECHNICAL FIELD

The invention concerns a device and a method for mixing the contents ofa tank, particularly in the food, beverage and pharmaceuticalindustries.

2. PRIOR ART

In the beverage industry it is well known to place nozzle devices insidea tank to mix the contents of a tank and to pump quantities of thecontents of the tank through the nozzle. This creates a flow within thetank which mixes the contents of the tank.

WO 2011/147958 A1 discloses a method for accelerated fermentation and adevice for mixing tank contents. The device comprises a jet pumparranged at a certain height in the lower part of a fermentation tank tomix the contents of the tank. For mixing, the tank contents arewithdrawn at the tank outlet and fed to the jet pump as a propellant bymeans of a pump. In the jet pump, a quantity of tank contents is suckedin by the propellant, mixed with the propellant and injected upwardsinto the tank, where a further mixing of the tank contents takes place.

The device of the WO 2011/147958 A1 is therefore well able to mix thecontents of a tank and to keep fermentation yeast in a fermentation tanksuspended during beer production. However, this mixing must be stoppedif the tank is to be emptied.

In cold hopping, the so-called “dry hopping”, hops is added to a tankwith a beer or a beer precursor. The aim is to dissolve special aromacomponents from hops in beer or in the beer precursor. Ideally, the hopsshould be finely distributed within the beer to produce a large surfacearea and good mass transfer. The hops product used for dry hopping isusually provided in the form of hops pellets, i.e. ground and pelletizedhop cones. Such hops pellets decompose on contact with liquid into acrumbly structure with particle sizes in the range of about 100-3000 μm.The suspension of hops particles must be maintained for a certain periodduring dry hopping, with the hops showing a tendency to sedimentation.It is therefore necessary to mix the tank contents as well as possibleduring dry hopping. Since the hops particles should not sediment evenduring the discharge of the tank contents, which can take a considerabletime with the usual large tanks, the mixing should also be maintainedduring the discharge, which is not possible with prior art mixingdevices. The drained suspension “hops in beer” should have only a smallsolids concentration so that the hops particles can then be filtered outof the suspension by means of a centrifuge or a separator without greatloss of beer.

It is therefore the task of the present invention to provide a deviceand a method for mixing the contents of a tank, which easily ensuresmixing of the contents of the tank under different process conditions.For example, mixing should be ensured during the processing time withinthe tank, after a preceding sedimentation phase, during a partialsedimentation phase and also when the tank is discharged.

3. SUMMARY OF THE INVENTION

The above tasks are solved by a device for mixing a tank contentaccording to patent claim 1 and by a method for mixing a tank contentaccording to patent claim 12.

The above-mentioned tasks are in particular solved by a device formixing the contents of a tank comprising a first pipe connecting bodyarranged on a connecting flange of a tank, a riser pipe extendingthrough the first pipe connecting body into the tank, a mixing pipeextending through the first pipe connecting body into the tank and apump, whose outlet can be connected at least to the mixing pipe andwhose inlet can be connected both to the first pipe connecting body andto the riser pipe. A pipe connecting body is any type of connectingelement for a pipe with a tank. These can be e.g. so-called Variventconnection elements, but also pipe bends, T-pieces or similar elements.

This allows the device to be used flexibly and allows the tank contentsto be withdrawn for mixing either from the first pipe connecting body orfrom the riser pipe and fed to a mixing nozzle located inside the tankby means of a pump. Since the inlet of the pump can also be connected tothe riser pipe, it is possible to mix the tank contents simultaneouslywhile the tank is being drained via the pipe connecting body. On theother hand, the fact that the inlet of the pump can be connected to thepipe connecting body also enables complete mixing of the tank contents,since in this case the tank contents are withdrawn at the lowest pointof the tank for mixing. In addition, by connecting the riser pipe to theinlet of the pump, it is also possible to mix the tank contents if partof the tank contents is to sediment intentionally at the same time orprior to this and this part is no longer to be swirled up or mixed. Thisdevice can therefore be used in a wide variety of operating modes, suchas mixing during discharge or mixing after or during sedimentation ofpart of the tank contents. The device therefore enables new processingand mixing techniques which can be used in dry hopping in beerproduction.

Preferably, the outlet of the pump can also be connected to the firstpipe connecting body if the inlet of the pump is connected to the riserpipe. This connection option makes it possible to loosen or dilutesediment that has accumulated after a sedimentation step at the deepestpoint of the tank, particularly in the area of the pipe connecting body,so that it can be removed more easily afterwards, for example. This alsomakes it possible to dilute sediment again to such an extent that thetank contents can subsequently be completely or partially mixed via themixing pipe or a mixing nozzle without there being any risk of cloggingof the mixing pipe and the mixing nozzle. Already sedimented solids cantherefore be mixed completely or partially with the remaining tankcontents.

Preferably, the outlet of the pump can also be connected to the riserpipe if the inlet of the pump is connected to the first pipe connectingbody. This connection option allows, for example, a gentle partialmixing of the lower tank contents without using the mixing pipe, whichhas a strong mixing effect on the tank contents. This solution can alsobe used if large volume flows are to be circulated within the tank. Thisis necessary, for example, if a heat exchanger is installed in the pipebetween the first pipe connecting body and the riser pipe. Since thecooling of tanks usually has to be performed quickly, high mass flowshave to be cooled. In most cases, these cannot be routed via the mixingpipe, as the dimensions of the mixing pipe may not be sufficient. Thesame applies of course to heating processes.

Preferably, the mixing pipe runs inside the riser pipe, furtherpreferably concentrically inside the riser pipe. This makes it possibleto connect the mixing device to an ordinary connecting flange of a tank,in particular a cylindroconical tank (CCT), without structurallychanging the tank itself. This means that every CCT can be equipped orretrofitted with a mixing device according to the invention in a simpleand reversible manner. The description explains the invention by meansof a CCT. However, it can also be used for tanks with any other bottoms,e.g. dished bottoms or flat bottoms. When reference is made to aconnection flange, reference is also made to welded connections.

Preferably, the riser pipe extends essentially vertical upwards into thetank and/or has an open end. This allows the riser pipe to be used forsuction of tank contents at an elevated liquid level. On the other hand,the riser pipe can also be used as an outlet at an elevated liquid levelfor mixing tank contents.

Preferably, the device also comprises a deflection plate attached to theriser pipe above the first pipe connecting body. Sediment is thus betterstirred up and diluted when the tank content, which was withdrawn viathe riser pipe, is again introduced into the tank via the pipeconnecting body.

Preferably, a mixing nozzle is connected to the upper end of the mixingpipe. The mixing nozzle can be used to shape the jet of the tankcontents introduced into the tank in order to achieve better mixing ofthe tank contents.

Preferably, the mixing nozzle is a jet pump which is adapted to drawtank contents out of the tank and mix them with tank contents which arepumped via the mixing pipe to the mixing nozzle. This allows the mixingnozzle not only to inject the tank contents pumped to it into the tank,but also to mix them with other tank contents, which are sucked in bythe mixing nozzle itself. Thus, a very intensive mixing of the tankcontents is possible.

Preferably, the mixing pipe can further be used to withdraw tankcontents. If the mixing nozzle or jet pump is left out and the end ofthe mixing pipe protrudes into the tank without attachments, this canalso be an advantage. Then, the mixing pipe can also be used to withdrawthe tank contents. This tank contents can then be returned to the tankvia the riser pipe and/or the first pipe connecting body, or the tankcontents can be discharged from the tank in this way.

This then allows the introduction and/or withdrawal of tank contents ata further level into the tank. For the first time, this allows evengreater flexibility when using a tank for beer preparation.

Preferably, the lower end of the riser pipe is connected to a secondpipe connecting body. This allows the riser pipe to be integrated intothe liquid circuit via standardised means.

Preferably, the riser pipe is shorter than the mixing pipe. Thus theupper end of the mixing pipe or the mixing nozzle within the tank isarranged at a higher level compared to the end of the riser pipe. Thisprovides different mixing types, depending on whether the riser pipe orthe mixing nozzle is used as an outlet.

Preferably, the riser pipe extends at least by a length of 0.5 m, orpreferably by at least a length of 1 m, or preferably by at least alength of 1.5 m into the tank, measured from the connecting flange.

Preferably, the mixing pipe, preferably including the mixing nozzle,extends into the tank by a length of at least 0.7 m, or preferably by alength of at least 1.2 m, or preferably by a length of at least 1.7 m,measured from the connecting flange. These lengths of riser pipe andmixing pipe, including mixing nozzle if necessary, are particularlyadvantageous when mixing hops particles or yeast cells in a fermentationtank during beer production. The lengths can depend on the tank size andthe tank geometry.

Preferably, the first pipe connecting body is further connected to aninlet and outlet line for filling and emptying the tank. This allows thetank to be filled and emptied via the first pipe connecting body,especially if the tank contents are mixed at the same time. However,this inlet and outlet line does not necessarily have to be connecteddirectly to the pipe connecting body.

An indirect connection is also possible. Inlet and outlet lines can alsobe combined or can be separated from each other.

The above tasks are also solved by a method for mixing the contents of atank, comprising the following steps:

-   a. Arranging a riser pipe extending through a first pipe connecting    body on the connecting flange into the tank;-   b. Withdrawing the tank contents either via the riser pipe or via    the first pipe connecting body arranged on an outlet flange of the    tank;-   c. Pumping the tank contents withdrawn via the riser pipe or via the    first pipe connecting body by means of a pump;-   d. Connecting the outlet of the pump so that both the tank contents    withdrawn via the riser pipe or the first pipe connecting body can    be introduced into the tank via a mixing pipe extending through the    first pipe connecting body into the tank and the tank contents    withdrawn via the riser pipe can be introduced into the tank via the    first pipe connecting body; and-   e. Introducing the withdrawn tank contents into the tank and mixing    the withdrawn tank contents with the remaining tank contents.

This method makes it possible to return the tank contents withdrawn fromthe tank to the tank via the mixing pipe as well as via the first pipeconnecting body. The tank contents can be mixed when introduced via themixing pipe and sedimentation of solids can be completely or partiallyprevented. Partial sedimentation is possible if the tank contents arewithdrawn via the riser pipe and fed back via the mixing pipe. Completemixing, on the other hand, occurs when the tank contents are withdrawnvia the first pipe connecting body and fed back via the mixing pipe.

Furthermore, sediment accumulated in the lower area of the tank can bediluted or whirled up again and mixed if the tank contents are withdrawnvia the riser pipe or the mixing pipe and introduced via the first pipeconnecting body. The method according to the invention therefore allowsthe flexible use of the mixing device for different mixing tasks. Inparticular, the process can also be used to carry out new processing,mixing or sedimentation processes, which can be advantageously used indry hopping for beer production, although the method is not limited tosuch application.

Preferably, the method comprises the step of draining tank contents fromthe tank via the first pipe connecting body, if in step b. the tankcontents are withdrawn via the riser pipe, whereby draining and mixingtake place simultaneously. This simultaneous mixing and drainingprevents sedimentation within the tank during the draining process. Thisensures a homogeneous suspension of solids in the drained liquid, as isnecessary, for example, for the removal of hops particles by acentrifuge or a separator during dry hopping.

Preferably, the method further comprises the step of swirling up thesediment of the tank contents if in step b. the tank contents arewithdrawn via the riser pipe and the outlet of the pump is connected tothe first pipe connecting body. This allows sediments accumulated in thelower part of the tank to be specifically swirled up or diluted in orderto drain them better or to mix them again with the contents of the tank.

Preferably, the method is uses for dry hopping, where the tank is afermentation tank and the tank contents contain hops particles. Themethod can be used particularly advantageously for dry hopping in beerproduction, in particular for homogenizing the hops particles in theliquid even during the time-consuming draining process.

4. SHORT DESCRIPTION OF THE DRAWINGS

In the following preferred embodiments of the invention are describedwith reference to the drawings, wherein:

FIG. 1: shows a sectional side view of a lower portion of acylindroconical tank having an embodiment of a device for mixing thetank contents and a schematic representation of further components ofthe device in an operating mode for mixing the tank contents;

FIG. 2: shows the device according to FIG. 1 in another operating modeduring mixing the tank contents;

FIG. 3: shows the device according to FIG. 1 in another operating modeduring diluting or whirling up sediment;

FIG. 4: shows a three-dimensional partial view of a lower region of acylindroconical tank having an embodiment of a device for mixing thecontents of the tank; and

FIG. 5: shows a cut side view of the lower part of the tank of FIG. 4,with parts of the device for mixing the tank contents in detail.

5. DESCRIPTION OF PREFERRED EMBODIMENTS

In the following, preferred embodiments of the invention are describedin detail with reference to the drawings.

FIG. 1 shows a lower part of a cylindroconical tank (CCT) 10 as used,for example, as a fermentation and/or storage tank of a brewery with adevice 1 for mixing tank contents. At the lower conical outlet area ofthe tank 10 a connection flange 14 is located to which a first pipeconnecting body 20 is connected. The tank 10 can be filled and emptiedvia a main pipe 90 which is connected to the tank 10 at this first pipeconnecting body 20. The connection flange 14 preferably has a nominaldiameter DN of 100 mm or larger.

As further parts of the device 1, a riser pipe 40 extends through theconnecting flange 14 into the tank 10. The riser pipe 40 is essentiallyaligned vertically and penetrates the opening of the connection flange14 preferably coaxially. The nominal diameter DN of the riser pipe ispreferably 65 mm. Via the riser pipe 40, the tank contents can bewithdrawn from tank 10 at a certain height or introduced into tank 10.At the lower end of the riser pipe 40, it is connected to a second pipeconnecting body 30, which hydraulically connects the riser pipe 40 tothe other parts of device 1.

In addition, a mixing pipe 50 extends through the connection flange 14into the tank. The mixing pipe 50 runs essentially coaxially inside theriser pipe 40 and is also vertically aligned. The upper end of themixing pipe 50 can be open, or a mixing nozzle 52 can be connected toit. The mixing nozzle 52 is preferably a jet pump 52, which itself cansuck the contents of the tank from tank 10 and mix them with thepropellant, which is fed to it through the mixing pipe 50. If no mixingnozzle 52 is installed on the mixing pipe 50, the mixing pipe 50 canalso be used to suck in tank contents.

The device 1 further comprises a pump 60 which can be connected indifferent ways to the first pipe connecting body 20, to the riser pipe40 and to the mixing pipe 50 by means of piping 92 and valves 71-80. Dueto the different interconnection options, different operating states ofthe device for mixing, sedimentation and cleaning (Cleaning In Place,CIP) can be set.

For filling or emptying the tank without simultaneous mixing, valve 71is open and all other valves are closed.

To mix the tank contents in a first operating mode, as shown in FIG. 1,the valves 73, 76 and 77 are open and the other valves are closed. Theinlet 62 of the pump 60 is thus connected to the riser pipe 40 via thesecond pipe connecting body 30. The outlet 64 of the pump 60 isconnected to the lower end of the mixing pipe 50. Thus the tank contentis withdrawn via the riser pipe 40 and fed to the pump 60. The pump 60is in operation and pumps the withdrawn tank contents to the mixing pipe50, which introduces the tank contents at a raised position into thetank 10 and thus ensures mixing of the tank contents. Depending on thepower of the pump 60, partial sedimentation can also be achieved in thearea below the upper end 42 of the riser pipe 40. The power of the pump60 can be controlled by a speed control 83 of the pump 60.

The mixing of the first operating mode can also be carried out duringthe discharge of tank contents from tank 10. In this case the pump 60 isin operation and the valves 71, 73, 76 and 77 are open and the othervalves are closed. This ensures a homogeneous distribution of suspendedparticles in the liquid even during discharge. This operating mode canalso be carried out when filling the tank in order to mix the tankcontents during filling.

In another operating mode shown in FIG. 2, valves 72 and 77 are open,the other valves are closed and the pump is in operation. Thus, theinlet 62 of pump 60 is connected to the first pipe connecting body 20and the outlet 64 of pump 60 is connected to the mixing pipe 50. In thisoperating mode, the tank contents are therefore withdrawn at the lowestpoint of tank 10 and fed back to the tank via mixing pipe 50 or a mixingnozzle 52 connected to it. This results in optimum mixing of the entiretank contents of the tank 10.

In another operating mode shown in FIG. 3 the valves 73, 75 and 76 areopen, the other valves are closed and the pump 60 is in operation. Theinlet 62 of pump 60 is thus connected to riser pipe 40 and the outlet 64of pump 60 is connected to the first pipe connecting body 20. In thismode, sediment deposited in the lower part of tank 10 can be whirled upor diluted so that it can subsequently be better removed from tank 10 orremixed with the tank contents. To improve the turbulence of thesediment, a deflection plate 70 is attached to the riser pipe 40 justabove the first pipe connecting body 20. This swirls the flow of tankcontents coming from the pipe connecting body 20 so that the sediment isbetter captured.

In another operating mode (not shown) the valves 72, 76 and 79 are open,the other valves are closed and the pump 60 is in operation. Thus, theinlet 62 of pump 60 is connected to the first pipe connecting body 20and the outlet 64 of pump 60 is connected to the riser pipe 40. In thisoperating mode, the withdrawn tank contents are introduced via the riserpipe 40 and thus at a lower level than via the mixing pipe 50 or themixing nozzle 52. In this operating mode, mixing can therefore becarried out more gently than via the mixing nozzle 52. This operatingmode can also be used for a cooling process, for example, since largemass flows are required therefore.

These mass flows may no longer be conveyed through the mixing pipe 50but must be introduced into the tank via the riser pipe 40. A necessaryheat exchanger (not shown) is then variably integrated into any pipeoutside the tank. One conceivable location, for example, would bebetween pump 60 and valve 79.

Altogether, the inventive device 1 can be used to connect the mostvaried operating modes, so that device 1 can be used for the most variedmixing and sedimentation applications, particularly in the beverage andfood industries. Device 1 or the process carried out with it canpreferably be used in the different operating modes for dry hopping in abeer brewing process.

The device is also suitable for Cleaning In Place (CIP). For CIP ofmixing pipe 50 and mixing nozzle 52, valves 72, 73, 74 and 77 are openand the other valves are closed. Pump 60 is in operation at CIP.

For CIP the riser pipe 40, valves 72, 76 and 79 are open, the othervalves are closed and the pump 60 is in operation.

For CIP of valve 75, valves 72, 73, 74 and 75 are open, the other valvesare closed and pump 60 is in operation.

To drain the CIP liquid from device 1 and from tank 10, all valves 71-80are open and pump 60 is not operating.

Device 1 also has measuring instruments 81, 82 and 84, such as volumeand/or mass flowmeters, temperature meters, pH meters, pressure gauges,turbidity and/or colorimeters or other measuring instruments for thebeverage industry. The exact number and arrangement of measuringinstruments is arbitrary.

The invention claimed is:
 1. A device for mixing the contents of a tankcomprising a. a first pipe connecting body arranged on a connectingflange of a tank; b. a riser pipe extending through the first pipeconnecting body into the tank; c. a mixing pipe extending through saidfirst pipe connecting body into said tank; d. a pump whose outlet isconnected at least to the mixing pipe and whose inlet is connected bothto the first pipe connecting body and to the riser pipe; and e. adeflection plate secured to the riser pipe above the first pipeconnecting body; wherein the deflection plate is located at a bottom ofthe tank and below an upper end of the riser pipe.
 2. The deviceaccording to claim 1, wherein the outlet of the pump is also connectableto the first pipe connecting body when the inlet of the pump isconnected to the riser pipe.
 3. The device according to claim 1, whereinthe outlet of the pump is also connectable to the riser pipe when theinlet of the pump is connected to the first pipe connecting body.
 4. Thedevice according to claim 1, wherein the mixing pipe runs inside theriser pipe, preferably concentrically inside the riser pipe.
 5. Thedevice according to claim 1, wherein the riser pipe extendssubstantially vertically upward into the tank and/or has an open end. 6.The device according to claim 1, wherein the mixing pipe is furtherusable for withdrawing tank contents.
 7. The device according to claim1, wherein a mixing nozzle is located inside the tank and connected tothe upper end of the mixing pipe.
 8. The device according to claim 7,wherein the mixing nozzle is a jet pump adapted to withdraw tankcontents from the tank and mix it with tank contents pumped via themixing pipe to the mixing nozzle.
 9. The device according to claim 1,wherein the lower end of the riser pipe is connected to a second pipeconnecting body.
 10. The device according to claim 1 wherein the riserpipe is shorter than the mixing pipe.